docs: def _detach(cls, disk_id):
          """ Detach a disk from a vm. """
          disk = cls._info(disk_id)
          opers = []
          if disk.get('vms_id'):
              for vm_id in disk['vms_id']:
                  cls.echo('The disk is still attached to the vm %s.' % vm_id)
                  cls.echo('Will detach it.')
                  opers.append(cls.call('hosting.vm.disk_detach',
                                        vm_id, disk_id))
          return opers